BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a push-on connector used as an optical connector or a coaxial cable connector.
2. Prior Art Description
The assignee of the present invention had proposed a locking construction of such a connector in a Japanese utility model application No. 21,277/87 dated Feb. 18, 1987 (opened No. 164,183/88 opened on Oct. 26, 1988).
FIGS. 1 and 2 of the published utility model show the prior art connector namely push-on connector having the locking construction.
In order to help a better understanding of the present invention, the prior art will be explained at first. FIG. 1 shows in general the locking construction of the connector of the utility model. In FIG. 1, A indicates an adaptor or female connector and B indicates a plug or male connector to be inserted and mated with the adaptor A. Between a
coupling 7 and a connector body of the plug B, a
slide ring 10 is provided. The diameter of the
slide ring 10 is so selected to abut against a
stopper 2 provided in the adapter A on its entire periphery or divided into a plural number. The FIGURE shows a case of providing the
stopper 2 on the entire periphery of the adaptor A. Furthermore, a
spring member 11 is provided between the
slide ring 10 and the
body 3 by which
spring member 11 the
slide ring 10 is depressed or biased towards the direction of the adapter A. Also at the inner periphery of the
coupling 7, a
stopper ring 12 is provided. A
stopper 13 is provided around the outer periphery of the
slide ring 10 to engage with the
stopper ring 12 and by which the outer extreme position of the
slide ring 10 is limited. By this arrangement, the
slide ring 10 normally occupies a position to cover an engaging
reentrant portion 4. In FIG. 1, 14 of the plug B shows a ferrule to hold an optical cable at its center and 1a of the adapter A shows an axial slit provided in the
body 1 and 15 is a slit sleeve and 16 is a stopper.
In the above construction of the connector, when the plug B is inserted into the adapter A by holding the
coupling 7, the
stopper 2 of the adapter A depresses the front end surface of the
slide ring 10 against the spring force of the
coil spring member 11. The
slide ring 10 moves backward towards the
holding portion 8 of the
cable 9 as can be seen from FIG. 2a so that the
stopper 2 of the adapter A falls into the engaging
reentrant portion 4 as can be seen from FIG. 2b. Then the
slide ring 10 restores its original position by the bias force of the
coil spring 11 and covers outer periphery of the
stopper 2 engaging by dropping into the engaging
reentrant portion 4 so as to prevent disengagement of the connectors and thus the connection and locking motion is completed. At dislocking the connector and its connection, contrary to the above operation the
coupling 7 is pulled backwardly. Then the
stopper ring 12 of the
coupling 7 presses the
stopper 13 of the
slide ring 10 against the bias force of the
spring 11 towards the
holding portion 8 of the
cable 9 to expose the
engaging reentrant 4. By the further pulling force applied to the
coupling 7, the
stopper 2 of the receptacle A is disengaged from the
engaging reentrant 4 so that the connectors are uncoupled and the connection is broken at the same time.
This kind of the connector provided with the locking construction can be handled easily for its two kind of operations i.e. locking and connecting by holding only the
coupling 7 so that it has an advantage of simple handling in a single operation to avoid a double operation. However, during actual use thereafter it has shown up points still to be solved and improved.
At the disengagement motion of the locked connector in the above locking construction, as has been explained, the
coupling 7 is pulled backwards and by this pulling force, the
slide ring 12 is retracted against the bias force of the
coil spring 11 towards the
holding portion 8 and by a further pulling force the
stopper 2 disengages from the engaging
reentrant portion 4 to dislock the locked connector. At this time, all the dislocking force is conveyed to various portion of the connector via the
spring 11.
In other words, all the dislocking force is loaded to the
spring 11 so that after a number of coupling and uncoupling operations of the connector, the
spring 11 may have a permanent deformation and the bias force to be applied to the
stopper 13 is decreased gradually. This phenomenon is so-called "fatigue of spring".
This fatigue of spring can be avoided by selecting the spring member within a certain condition. But by the recent requirement of miniaturization of connectors, the space accommodating the spring member is narrowly limited thus the selection of the spring becomes more and more difficult.
SUMMARY OF THE INVENTION
The present invention is to solve the above-mentioned problems of the prior art push-on connector. More especially, the present invention offers a novel structure of the push-on connector having no fear of causing fatigue of spring at dislocking of the locked connector so that a spring suitable to the locking construction can be selected with more freedom.
In the push-on connector of the present invention, when a pulling force is applied to the
coupling 7, the
slide ring 10 retracts towards the
holding portion 8. But the retractable distance is so selected that the distance is greatest than a distance from the top of the
slide ring 10 to a position to expose the engaging
reentrant portion 4 and less than the limit causing fatigue of the spring. For this purpose an abutting member or
portion 5 is provided between the
slide ring 10 and the
connector body 3 of which position is selected to satisfy the above condition of the retracting distance.
The limit of fatigue of the spring can be obtained by actual experiments and from the amount of compression and restoration. However, it may be more convenient to estimate an amount of 80% of tolerable torsion stress defined under the standard of JIS B2704 (1987).
The extent of exposure of the
engaging reentrant 4 may be enough to allow the
stopper 2 of the adapter A to drop into it or to separate from it.
By the construction having the abovementioned abutting
member 5, a considerable portion of the disengaging force required for dislocking and uncoupling is accepted by the abutting
member 5 and the
spring member 11 will not receive a compressive force exceeding the limit of its fatigue.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1, 2a and 2b show one example of the prior art push-on connector in the partial cross-section and enlarged views;
FIG. 3 is a cross-sectional view of plug of the connector of the invention in an enlarged scale; and
FIGS. 4 to 6 show further modified embodiment of the connector according to the present invention.
DETAILED EXPLANATION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The invention will be explained by referring to FIGS. 3 to 6 showing embodiment thereof.
FIG. 3 shows an overall cross-sectional view. FIGS. 4 to 6 are similar view with FIG. 2.
FIG. 3 shows one embodiment of a coaxial connector being applied with the present invention. A
central contact 17 of a coaxial cable is fixed by a supporting
insulator 18 of a
connector body 3. A
cylindrical slide ring 10 is provided to cover the whole outside of the
connector body 3. This
slide ring 10 is normally biased towards the outside or left side of the drawing from said
connector body 3 by a
compressed coil spring 11. The forward pressing force of the
coil spring 11 is stopped by a
stopper ring 12 abutting against a
stopper 13 provided at bottom end of the
slide ring 10. Thus the
slide ring 10 is not pushed out in a forward direction beyond a certain position.
Between the bottom end surface 10' of the
slide ring 10 and a vertical surface of a flange portion of the
connector body 3 against which both ends of the
coil spring 11 are abutted, there is provided an abutting member or
portion 5 being a step portion in the outer periphery of the
body 3 in this embodiment. In an actual embodiment, the outer diameter of this coaxial connector is about 10 mm and its overall length is about 30 mm and the axial length of the accommodating space of the
coil spring 11 is about 5.5 mm. The diameter of the
connector body 3 at a portion mounting the
coil spring 11 is about 6 mm or less. A step portion or an
abutting member 5 having a height of about 0.3 mm is provided on the
connector body 3 at a location of 2 mm measured from the bottom surface 10' of the
slide ring 10 contacting with the
coil spring 11 in its normal position towards a
cable holding portion 8. If the
slide ring 10 is retracted towards the cable holding side, the end surface 10' of the
slide ring 10 contacting the
coil spring 11 abuts against the abutting
portion 5 so that the
slide ring 10 will no longer retract after its backward stroke of about 2 mm so that the
coil spring 11 will not be depressed further.
In FIG. 3,
reference numeral 6 indicates a stop ring fixed by a thread joint with the
coupling 7. This
stop ring 6 prevents the
coupling 7 being slid off and detached from the
connector body 3.
Reference numeral 19 indicates a stop ring fixed by a thread-in the
body 3 and securing the supporting
insulator 18.
FIG. 4 shows a slightly different embodiment of the present invention, in which a cylinder or a ring is provided at the outer periphery of the
body 3 and at inside of the
coil spring 11 so that an
abutting member 5 is formed to have the same function with the embodiment shown in FIG. 3. In this embodiment, an advantage obtained is in that the existing push-on connector is once dismantled and after arranging the cylinder on the ring on the
body 3 reassembled and the fatigue problem of the spring can be avoided.
FIG. 5 shows another embodiment of the present invention. In this embodiment, the abutting
member 5 is formed by providing a projecting member extending from the end surface of the
stopper 13 of the
slide ring 10 towards the
cable holding portion 8.
It is preferred to form this projecting member in a form of a tubular shape, however, 3 to 5 studs may be provided equidistantly around the periphery of the
stopper 13 of the
slide ring 10.
FIG. 6 shows a till further embodiment, in which the abutting
member 5 is formed in the shape of a projection extending from right top portion of the
body 3 towards the
slide ring 10 as shown in the drawing.
At the same time, a recess is provided inside the said projection into which the
coil spring 11 is accommodated. By providing such a recess, the housing space of the coil spring can be made larger or longer so that a greater freedom for the selection of the coil spring member can be obtained.
Function of said projection is just same as the abutting
member 5 shown in FIG. 3 or FIG. 5.
By providing the aforementioned projection or abutting
member 5 according to the present invention, it is possible to completely remove the possibility of occurrence of fatigue of the
coil spring 11 and thus heretofore existing limitation for selecting the type and kind of
coil spring 11 can be remarkably decreased so that the use of a too hard spring or a too soft spring material can be avoided. Also the mating or disengaging operation can be done with ease and the feeling for handling the connectors can be much improved.
A further advantage of the present invention is that the invention can be applied also to the existing prior art push-on connectors by adding a very minor modification thereto.